I input \vec x but it doesn't change a vector x.

What is the wrong?

In addition to it, I couldn't input \ldot.

[Edit, JL] Really? $\vec{x}, \vec{y}$ Works for me!

Oh, I did not know that I should use $ for every format.
Thanks a lot .


  • 1
    $\begingroup$ I added the TeX-code to your post. Take a look! What is \ldot supposed to do? I have used \cdot, as in $\vec{x}\cdot\vec{y}$, and \ldots, when I type set a list like $1,2,\ldots,n$. But what is \ldot? $\ldot$ is an unrecognized command and is displayed in red to indicate an error. $\endgroup$ Oct 17, 2016 at 16:33
  • $\begingroup$ Even in $\rm\LaTeX$ you need to use dollar signs (or \(\) and \[\], which I think you can also use here.) $\endgroup$
    – Asaf Karagila Mod
    Oct 17, 2016 at 16:41

1 Answer 1


Inline latex code needs to be enclosed in dollar signs: $\vec x$ gives $\vec x$. Out of line formulas can be enclosed in double dollar signs: $$\vec x$$ gives $$\vec x$$


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